DUESSELDORF, Germany (Reuters) - A German Islamist preacher was sentenced on Wednesday to 5-1/2 years in prison on four counts of supporting a foreign terrorist organisation.

Prosecutors said Sven Lau served as an "extended arm" of the Jaish al-Muhajireen wal-Ansar, an insurgent group made up of around 1,500 Chechen, Uzbek and Tajik fighters, which in 2015 pledged allegiance to the Nusra Front, then an al Qaeda affiliate. They said he collected funds and recruited fighters for the group, which is listed as a terrorist organisation in Germany.

Lau, a hardline Muslim preacher from Germany's western state of North-Rhine Westphalia, had also turned up in the city of Wuppertal with nine supporters in tow, all wearing orange vests emblazoned with the words 'Sharia Police'.

Prosecutors said this was an illegal gathering as he and eight others were trying to recruit others to join them.

Prosecutors had called for a 6-1/2 year prison sentence for Lau, while the defence had pleaded for an acquittal.